Transmission input shaft speed measuring assembly

ABSTRACT

A device for sensing the input shaft speed of an automotive automatic transmission that is driven by the engine through the fluid coupling of a torque converter. The speed sensor device includes circumferentially spaced markings about the transmission input shaft and a speed sensor that is placed at close proximity to the circumferentially spaced markings through a hole in the torque converter stator shaft. An electronic control unit (ECU) analyzes the sensor output signal and in the case of an active speed sensor it also functions as its power source. During vehicle operation, the transmission input shaft rotates the target wheel in front of the speed sensor causing modulation of its output signal. The electronic control unit analyzes the signal modulation and calculates the input shaft rotational speed. A variety of sensor/target-wheel options and sensor mounting techniques could be used depending on the application constraints.

This application claims the benefit of U.S. Provisional PatentApplication No. 60/490,377 filed on Jul. 25, 2003.

BACKGROUND

Knowledge of input and output shaft speeds for an automatic transmissionwould enable its control unit to execute smooth transmission shiftsleading to enhanced vehicle performance. Although output-shaft speedmeasurement of an automatic transmission is easily accomplished, speedmeasurement of its input shaft is difficult due to the transmissioncomplexity and its input shaft inaccessibility. Current methods forinput-shaft speed measurement, such as the ones described in U.S. Pat.Nos. 6,522,133B1, 4,586,401 and 3,845,671, require a magnetic sensorthat senses either the rotation of a large magnetic target wheel througha non-ferromagnetic reaction shell or the rotation of a transmissionoutput gear. These solutions require sensors that are bulky andexpensive for sensing rotating target wheels at great distances,expensive magnetic target wheels due to their large size, the use of anexpensive non-ferromagnetic reaction shell, and placement of sensorsthrough a hole on the transmission housing that requires robust sealingmethods. Also, in certain designs where the large air-gap between thesensor and the target wheel requires the choice of a VR speed sensor,the resulting output signal does not allow low speed measurements.

SUMMARY

The present invention relates to a device for sensing the speed of anautomotive automatic transmission input shaft that is part of atransmission input assembly. The transmission input assembly comprises atransmission input shaft, the associated transmission torque converterstator shaft, and the corresponding transmission pump housing. Thedevice comprises a sensor positioned adjacent the input shaft andconfigured to sense a plurality of markers circumferentially spacedabout the input shaft. The circumferentially spaced markers may beformed directly in the input shaft or may be provided by a target wheelattached onto the transmission input shaft having a plurality of markerscircumferentially spaced about the wheel. For example, the markers maybe metallic teeth or a series of alternating magnetic poles around thewheel's outer diameter (“OD”) surface. The speed sensor is placed atclose proximity to the circumferential markers through a hole in thetorque converter stator shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view in partial section of a transmissioninput assembly incorporating a speed sensing device according to a firstembodiment of the present invention;

FIG. 2 is a top plan view of a transmission input shaft having aplurality of circumferential markings formed thereon;

FIG. 3 is a cross sectional view along the line 3-3 in FIG. 2;

FIG. 4 is a top plan view of the transmission input shaft and theassociated transmission torque converter stator shaft of FIG. 1;

FIG. 5 is an isometric view of the transmission input shaft and theassociated transmission torque converter stator shaft of FIG. 1 with thespeed sensor device according to the first embodiment positionedtherewith;

FIG. 6 is an isometric view of the transmission input shaft assembly ofFIG. 1 with the speed sensor device according to the first embodimentpositioned therewith;

FIG. 7 is a side elevation view of a gear ring useable as a target wheelin the present invention;

FIG. 8 a is a side elevation view and FIG. 8 b is a front elevation viewof a cage ring useable as a target wheel in the present invention;

FIG. 8 c is a side elevation view of a cage ring similar to that ofFIGS. 8 a and 8 b;

FIGS. 9-13 are side elevation views of various molded rings useable as atarget wheel in the present invention;

FIG. 14 a is a side elevation view and FIG. 14 b is a front elevationview of a molded ring with side ribs useable as a target wheel in thepresent invention;

FIG. 15 is a side elevation view in partial section of a transmissioninput assembly incorporating a speed sensing device according to asecond embodiment of the present invention;

FIG. 16 is a side elevation view in partial section of a transmissioninput assembly incorporating a speed sensing device according to a thirdembodiment of the present invention;

FIG. 17 is a side elevation view in partial section of a transmissioninput assembly incorporating a speed sensing device according to afourth embodiment of the present invention;

FIG. 18 is a side elevation view in partial section of a transmissioninput assembly incorporating a speed sensing device according to a fifthembodiment of the present invention;

FIG. 19 is a side elevation view in partial section of a transmissioninput assembly incorporating a speed sensing device according to a sixthembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the invention is susceptible of embodiment in many differentforms, there is shown in the drawings and described in detailedpreferred embodiments of the invention. It is understood that thepresent disclosure is to be considered only as an example of theprinciples of the invention. This disclosure is not intended to limitthe broad aspect of the invention to the illustrated embodiments. Thescope of the protection should only be limited by the accompanyingclaims.

A first embodiment of the invention will be described with reference toFIG. 1-14. Referring to FIG. 1, the transmission input shaft assembly 10generally comprises an input shaft 12, a torque converter stator shaft14 positioned about the input shaft 12 and the transmission pump housing18 positioned about the input shaft 12 and the torque converter statorshaft 14. The torque converter stator shaft 14 typically includes aradial flange 16 extending adjacent the side wall of the pump housing18. The speed sensing device 20 generally includes a plurality ofcircumferentially spaced markings 22 about the input shaft 12 and asensor 24 extending through the torque converter stator shaft 14 inclose proximity to the circumferentially spaced markings 22.

Referring to FIGS. 1-6, the torque converter stator shaft 14 includes ahole 17 therethrough configured to receive the sensor 24. As seen inFIG. 4, the hole 17 is aligned with the circumferentially spacedmarkings 22 such that the sensor 24, positioned in the hole 17, will bealigned with and in close proximity to the circumferentially spacedmarkings 22. The sensor 24 has a body 27 configured to plug and seal thehole 17. To accommodate the cable 25 extending from the sensor 24, anaxial groove 19 extends along the torque converter stator shaft 14 fromthe hole 17 to a radial groove 21 extending along the torque converterstator shaft flange 16. As can be seen in FIGS. 5 and 6, the cable 25can be run through the grooves 19 and 21 and then along the wall of thepump housing 18 and out of the transmission assembly 10 withoutproviding substantial obstruction. A seal member 23 may be used to fillthe groove 19 to further ensure sealing of the hole 17.

The speed sensor cable 25 exits the transmission assembly 10 radiallyand is connected to an electronic control unit (ECU) that analyzes itsoutput signal. In the case of an active speed sensor, the ECU providespower to the sensor. As the circumferentially spaced markings 22 rotatewith the input shaft 12 in front of the speed sensor 24, the sensoroutput signal is modulated and the ECU calculates the input shaft 12rotational speed. The sensor 24 preferably has dual sensing elementswhich can, for example, be utilized for noise cancellation. In certainapplications where direction of rotation is also desired, the dualsensing elements may be configured to determine the direction ofrotation. In addition, the sensor 24 may be configured to provide atemperature measurement within the torque converter stator shaft 14.Commonly owned PCT Application No. PCT/US03/32692, herein incorporatedby reference, describes a system of obtaining a temperature measurementwith a VR sensor. Alternatively, a separate temperature sensor may beintegrated with the active speed sensor in order to provide temperaturemeasurement at a location deep inside the transmission interior.Depending on the design configuration, various hardware and software,for example, a specially designed ASIC, can be used.

Depending on the application constraints, the circumferentially spacedmarkings 22 can be provided in a variety of ways. For example, asillustrated in FIGS. 2 and 3, the circumferentially spaced markings 22can be defined around the input shaft 12 by machining, forming orotherwise providing splines into OD surface of the input shaft 12.Alternatively, the circumferentially spaced markings 22 can be providedby attaching a target wheel incorporating the markings 22 to the inputshaft 22. A variety of target wheels are illustrated in FIGS. 7-14. Thetarget wheel can be attached to the input shaft 12 in a variety of ways,for example, but not limited to, press-fitting, welding, or bolting ofthe target wheel onto the input shaft 12 OD surface.

The variety of illustrated target wheels will be described withreference to FIGS. 7-14. FIG. 7 illustrates a gear ring 30 with aplurality of teeth 31 that define the circumferentially spaced markings.The gear ring may be manufactured in various ways, for example, frompowdered metal or may be a stamped metal gear ring. FIGS. 8 a and 8 billustrate a stamped metal cage ring 32 made from one or more sectionsand having a plurality of openings 33 that define the circumferentiallyspaced markings 22. FIG. 8 c illustrates a stamped metal cage ring 32′similar to that shown in FIGS. 8 a and 8 b, with the cage ring 32′ beingformed in to halves 32 a and 32 b to facilitate positioning about theinput shaft 12. Each halve 32 a, 32 b has a projecting tab 39 and aretaining slot 41 for interconnection of the two halves 32 a, 32 b aboutthe input shaft 12. Other interconnection means may also be utilized.Additionally, the multi-piece configuration may be utilized for othertarget wheel types other than the stamped metal cage. For example, thesplit pair of magnetic rings 46 illustrated in FIG. 12 and describedhereinafter may be formed with interconnecting ends.

FIG. 9 illustrates a molded ring 34 with a plurality of spaced apartmetallic inserts 36 that define the circumferentially spaced markings22. FIG. 11 illustrates a target wheel similar to FIG. 9 but furtherincluding a protective rim 38 positioned thereabout. FIGS. 11-13illustrate molded multi-pole magnetic rings 40, 44 and 50 for use as thetarget wheel. The multi-pole magnetic ring 40 of FIG. 11 includes asplit 42 for facilitating positioning about the input shaft 12. Themulti-pole magnetic ring 44 of FIG. 12 includes a split pair of magneticrings 46 with a retaining band 48 thereabout. The multi-pole magneticring 50 of FIG. 11 is configured as an elastic member configured to beslipped over the input shaft 12. FIGS. 14 a and 14 b illustrates amulti-pole magnetic ring similar to that shown in FIGS. 11, 12 and 13,with protective ribs 52 positioned about the ring 50.

The sensor 24 can be any one of the available speed sensors such as a VRsensor, a Hall-Effect sensor, a Magnetoresistive sensor, a GMR sensor,or an Eddy Current sensor. The type of sensor 24 is selected to becompatible with the chosen circumferentially spaced markings 22. Forexample, if the circumferentially spaced markings 22 are defined byteeth formed around the normally ferromagnetic input shaft by machiningits OD surface, or a ferromagnetic gear-ring 30 target wheel is placedaround the input shaft 12, a VR sensor, a Hall sensor, aMagnetoresistive sensor, or a GMR sensor with a back-biased magnet canbe used. A multi-pole magnetic target wheel placed around the inputshaft 12 preferably utilizes a magnetic sensor without the back-biasedmagnet. Alternatively, an Eddy Current sensor is preferably utilizedwith circumferentially spaced markings 22 defined by a ferromagneticmaterial or a non-ferromagnetic conductive material.

Referring to FIG. 15, an alternate embodiment of the invention isillustrated. The circumferentially spaced markings 22 are providedaround the transmission input shaft 12 at a point along its axial lengthso that, in the final transmission assembly, the markings 22 aredirectly underneath the pump housing 18. The chosen sensor 24 is mountedover the circumferentially spaced markings 22 after the pump housing 18placement over the torque converter stator shaft 14 through an angledhole 17 from the pump housing sidewall to the stator 14 ID surface. Thesensor body 27 forms a sealed cylindrical plug inside the sensor hole 17and extends beyond the pump housing 18 sidewall. In the illustratedembodiment, the sensor body 27 is mounted to the stator radial flange 16by a clip 29 or the like. Alternatively, the sensor body 27 may besecured to the pump housing 18 or otherwise secured within the angledhole 17, for example, by an interference fit. Beyond the pump housing18, the sensor cable 25 exits the transmission assembly 10 radiallyrouted along the sidewall of the transmission pump housing 18.

Referring to FIG. 16, an alternate embodiment of the invention isillustrated. The circumferentially spaced markings 22 are providedaround the transmission input shaft 12 inside a slot 35 next to a fluidchannel 37. This may cause axial displacement of existing oil channelsfor certain applications. The chosen sensor 24 is mounted over thecircumferentially spaced markings 22 through a radial hole 17 on thebody of the torque converter stator shaft 14. The sensor body 27 forms asealed cylindrical plug inside the sensor hole 17 and extends beyond thestator OD surface in a way that allows its mounting onto the statorradial flange 16 or any other available mounting surface by a clip 29 orthe like. Beyond the stator flange 16, the sensor cable 25 exits thetransmission assembly 10 radially routed along the sidewall of thetransmission pump housing 18.

Referring to FIG. 17, an alternate embodiment of the invention isillustrated. The circumferentially spaced markings 22 are providedaround the transmission input shaft 12 inside a slot 35 next to a fluidchannel 37. This may cause axial displacement of existing oil channelsfor certain applications. The chosen sensor 24 is mounted over thecircumferentially spaced markings 22 through a radial hole 17 inside thetorque converter stator shaft flange 16. The sensor body 27 forms asealed cylindrical plug inside the sensor hole 17 and extends beyond thestator flange 16 in a way that allows its mounting onto the flange body.Beyond the stator flange 16, the sensor cable 25 exits the transmissionassembly 10 radially routed along the sidewall of the transmission pumphousing 18.

Referring to FIG. 18, an alternate embodiment of the invention isillustrated. The circumferentially spaced markings 22 are providedaround the transmission input shaft 12 at a point along its axial lengthso that, in the final transmission assembly, the markings 22 aredirectly underneath the pump housing 18. The pump housing 18 is formedwith a radial hole 43 extending from the pump housing 18 inner diameterto the pump housing 18 outer diameter. The hole 43 may be formed in thepump housing 18 or may be drilled in to a previously manufactured pumphousing 18. The pump housing radial hole 43 is aligned with a radialhole 17 in the torque converter stator shaft 14. The body 27 of thechosen sensor 24 is extended through the aligned radial holes 17 and 43such that a forward end of the sensor is mounted in close proximity tothe circumferentially spaced markings 22. The sensor body 27 forms asealed cylindrical plug inside the sensor hole 17. The other end of thesensor body 27 extends beyond the pump housing 18. In the illustratedembodiment, the sensor body 27 extends through a hole 62 of an oil pan60 positioned at the outer diameter of the pump housing 18. The oil pan60 has a removable cover 64 that can be removed to access the sensor 24.The sensor body 27 is removable from the radial holes 17 and 43 throughthe oil pan 60 to allow service or the like of the sensor 24. The sensorcable 25 extends from the sensor body 27 and exits oil pan 60 through asealed hole 66.

Referring to FIG. 19, an alternate embodiment of the invention isillustrated. The circumferentially spaced markings 22 are providedaround the transmission input shaft 12 at a point along its axial lengthso that, in the final transmission assembly, the markings 22 aredirectly underneath the pump housing 18, however, the markings 22 may bealternatively positioned. The chosen sensor 24 is mounted over thecircumferentially spaced markings 22 after the pump housing 18 placementover the torque converter stator shaft 14 through an angled hole 17 fromthe pump housing sidewall to the stator 14 ID surface. The sensor body27 forms a sealed cylindrical plug inside the sensor hole 17 and extendsbeyond the pump housing 18 sidewall. In the present embodiment, thesensor body 27 has an extended axial length configured to pass throughopen space in the transmission assembly 10. The extended sensor body 27is configured to extend to an easily accessible portion of thetransmission assembly 10, for example, a sealed hole 72 through thetransmission bell housing 70, or alternatively, through the removal ofthe oil pan or the like accessible component. A clip 29 or the like canbe provided to support a midsection of the sensor 24. The sensor cable25 extends from the sensor body 27 outside of the bell housing 70 fromwhere it routed to the ECU. If the sensor 24 requires servicing, it canbe easily withdrawn through the hole 72.

1. A device for sensing the speed of a rotating transmission input shaftpositioned within an associated torque converter stator shaft, thedevice comprising: a plurality of markers circumferentially spaced aboutthe input shaft; and a sensor, configured to sense the markers,positioned in close proximity to the circumferential markers through ahole in the torque converter stator shaft, wherein the torque converterstator shaft includes an axial body with a radial flange extendingtherefrom, and wherein an axial groove extends along the axial bodybetween the hole in the torque converter stator shaft and the radialflange.
 2. The device of claim 1, wherein a radial groove extends alongthe radial flange radially outward from the axial groove.
 3. The deviceof claim 2, wherein a cable extending from the sensor is retained withinthe axial and radial grooves.
 4. The device of claim 3, wherein atransmission pump housing having a radial wall is connected to theradial flange and the cable extends along the radial wall.
 5. The deviceof claim 1, wherein a seal member seals the axial groove.
 6. A devicefor sensing the speed of a rotating transmission input shaft positionedwithin an associated torque converter stator shaft, the devicecomprising: a plurality of markers circumferentially spaced about theinput shaft; and a sensor, configured to sense the markers, positionedin close proximity to the circumferential markers through a hole in thetorque converter stator shaft, wherein the torque converter stator shaftincludes an axial body with a radial flange extending therefrom, andwherein a transmission pump housing is mounted about the torqueconverter stator shaft and the sensor has a body extending beyond thetorque converter stator shaft axial body and a clip extends between thesensor body and the transmission pump housing to secure the sensor.
 7. Adevice for sensing the speed of a rotating transmission input shaftpositioned within an associated torque converter stator shaft, thedevice comprising: a plurality of markers circumferentially spaced aboutthe input shaft; and a sensor, configured to sense the markers,positioned in close proximity to the circumferential markers through ahole in the torque converter stator shaft, wherein the sensor isconfigured to sense the direction of rotation of the input shaft.
 8. Adevice for sensing the speed of a rotating transmission input shaftpositioned within an associated torque converter stator shaft, thedevice comprising: a plurality of markers circumferentially spaced aboutthe input shaft; and a sensor, configured to sense the markers,positioned in close proximity to the circumferential markers through ahole in the torque converter stator shaft, wherein the sensor isconfigured to sense a temperature adjacent the input shaft.
 9. A devicefor sensing the speed of a rotating transmission input shaft positionedwithin an associated torque converter stator shaft, the devicecomprising: a plurality of markers circumferentially spaced about theinput shaft; and a sensor, configured to sense the markers, positionedin close proximity to the circumferential markers through a hole in thetorque converter stator shaft, wherein the input shaft has an outersurface and the circumferential markings are formed integrally about theshaft outer surface.
 10. The device of claim 9, wherein thecircumferential markings include a plurality of splines about the shaftouter surface.
 11. A device for sensing the speed of a rotatingtransmission input shaft positioned within an associated torqueconverter stator shaft, the device comprising: a plurality of markerscircumferentially spaced about the input shaft; and a sensor, configuredto sense the markers, positioned in close proximity to thecircumferential markers through a hole in the torque converter statorshaft, wherein the circumferential markings are provided by a targetwheel positioned about the input shaft.
 12. The device of claim 11,wherein the target wheel includes a gear ring with a plurality ofcircumferentially spaced teeth.
 13. The device of claim 11, wherein thetarget wheel includes a metal cage ring having a plurality ofcircumferentially spaced openings.
 14. The device of claim 11, whereinthe target wheel includes at least two parts that are positioned aboutthe input shaft and interconnected to define a ring about the inputshaft.
 15. The device of claim 11, wherein the at least two partsincludes a multi-component multi-pole magnetic ring.
 16. The device ofclaim 11, wherein the target wheel includes a molded ring with aplurality of circumferentially spaced apart metallic inserts.
 17. Thedevice of claim 16, wherein the target wheel further includes aprotective rim positioned about the molded ring.
 18. The device of claim11, wherein the target wheel includes a multi-pole magnetic ring. 19.The device of claim 18, wherein the multi-pole magnetic ring includes asplit for facilitating positioning about the input shaft.
 20. The deviceof claim 18, wherein the multi-pole magnetic ring includes a split pairof magnetic rings with a retaining band thereabout.
 21. The device ofclaim 18, wherein the multi-pole magnetic ring is configured as anelastic member configured to slip over the input shaft.
 22. The deviceof claim 18, wherein the multi-pole magnetic ring includes protectiveribs positioned about the ring.
 23. A device for sensing the speed of arotating transmission input shaft positioned within an associated torqueconverter stator shaft, the device comprising: a plurality of markerscircumferentially spaced about the input shaft; and a sensor, configuredto sense the markers, positioned in close proximity to thecircumferential markers through a hole in the torque converter statorshaft, wherein a transmission housing is positioned about the device andthe sensor has a body extending from the torque converter stator shafthole to a hole in the transmission housing such that the sensor isremovable through the transmission housing hole.
 24. The device of claim23, wherein the sensor body seals the transmission housing hole.
 25. Thedevice of claim 23, wherein a support member supports a midsection ofthe sensor body.
 26. The device of claim 23, wherein an oil pan sealingcovers the transmission housing hole and removal of the oil pan providesaccess to the sensor body.
 27. An automatic transmission comprising: atorque converter shaft having a hole; a radially directed flangeextending from the torque converter shaft; an input shaft positionedwithin the torque converter shaft and having a plurality ofcircumferentially spaced markers; a pump housing positioned about thetorque converter shaft and adjacent the radially directed flange; and aspeed sensor securably positioned in the hole and in close proximity tothe circumferential markers.
 28. The automatic transmission of claim 27,further comprising securing means for affixing the speed sensor in closeproximity to the circumferential markers.
 29. The automatic transmissionof claim 28, wherein the securing means comprise clipping means formounting the speed sensor to the radially directed flange.
 30. Theautomatic transmission of claim 27, wherein the input shaft has an outersurface and the circumferential markings are formed integrally about theinput shaft outer surface.